This invention relates to a construction for uniting the brake case cover, rear wheel axle case and terminal speed reduction unit case of a tractor, and more particularly to the above-mentioned cover and cases made of sheet metal and joined together by welding.
Generally the brake case cover, rear wheel axle case and terminal speed reduction unit case of trctors are made by casting. However, because the casting operation is very cumbersome and entails pollution problems and castings add to the weight of the tractor, it is desired to produce the cover and cases from sheet metal. When formed from sheet metal, these parts are usually joined together by welding, with the resulting problem that the weld joints concentrically subjected to loads become brittle and are therefore very prone to damage. Although sheet metal of greater thicknesses may supposedly be usable for the cover and cases, the parts will then become heavier to nullify the advantage which would otherwise be derived from the use of sheet metal. Alternatively the portions susceptible to concentric loads may be reinforced with additional members, but this will greatly increase the number of the manufacturing steps.